Method of making zinc-white.



Patented Mar. I2, I91".

0. B. JONES. METHOD OF MAKING ZINE WHITE.-

(Application filed July 14, 1899.)

(No Model.)

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' ITED STATES PATENT union.

METHOD OF MAKING ZINC-WHITE,

SPECIFICATION forming part of Letters Patent No. 669,750, dated March12, 1901 Application filed July 14, 1899- $erial No. 723,773. (Nospecimens.)

. Zinc-White, of which the following is hereby declared to be a full,clear, and exact description.

In usual practice zinc-white is ordinarily obtained by subjecting thebroken ore and io.fuel admixed with a minor quantity of flux to theaction of an air-blast, the charge resting upon the grate-bars of thefamiliar Wetherell furnace. High-grade ores containing fifty per cent.or more of zinc are usually selected not I 5 only because of therelative cheapness of furnace management due to excess yield, but alsoby reason of the freedom of the ore from any large percentage of iron orother deleterious ingredient. The heat developed effects reduction ofthe iron, which thereupon fluxes and disappears in the slag. If the ironbe excessive, the slag becomes more copious and tends to unite thecharge as a matte on the fire-barsofthefurnace. Besides, theslagacts asa barrier to the free distillation of the zinc,

so that a considerable quantity is detained in the refuse gangue andbecomes lost.

The object of the present invention is to accomplish the economicutilization of zinc o ores of low grade for manufacture of zincwhitedespite the marked percentage of iron, 650., (e. 9., manganese,) withwhich the zinc ores are generally contaminated. Ores containingtwenty-five per cent. zinc, for exam- 3 5 ple, often carry an equal oreven higher content of iron, both elements being combined with sulfur toconstitute a poor zinc-blende or black jack of commerce.

In practice the selected ore is finely comminuted or powdered andadmixed with an equal or even greater quantity of fuel sufficient tosupport desired combustion. In conjunction with a minor addition ofusual flux, similarly reduced, the powdered mixture is 5 projected as acharge in divided masses by aid of an air-blast into the interior of anupright furnace, The direction of the blast is substantially tangential,so that the charge assumes a swirling or cyclonic motion within thefurnace, while the fuel, emerging in divided masses separate from eachother, bursts into flame and effects rapid reduction and conversion ofthe volatile zinc. The pigmentfumes escape at the furnace-throat intothe familiar collecting-chambers. Th ehigh heat and the swirling motioneffect the separation of the iron and other non-volatile constituentsfrom the zinc, these for the most part becoming slagged and on contactwith the furnacewalls falling away thereon to the pit beneath. A brightfire at the pit serves to start the furnace in action, but later on maybe diminished or be even dispensed with, except so far as may berequisite to keep the slag melted for occasional tapping.

On the accompanying drawings, Figure 1 is a longitudinal and Fig. 2 across-section view of one style of furnace properly suited for practiceof the invention.

As here shown, the furnace-body A is of taper or hopper like form,ending below in a slag-pit B and surmounted by a dome-top 0, havingescape-pipe D for discharge of the pigment-fumes into thecollecting-chambers. A chute E admits fuel to the pit B, and an ordinarybustle-pipe F, with twyers f, distribute the air-blast for thesubsidiary fire. At some distance above the contracted base or pitdelivery-pipes G project tangentially through the furnace-wall and byaid of an air-blast serve to feed the mixed charge of ore, fuel, andflux in divided masses at separate points within the furnace, a swirlingmotion being imparted to the charge by reason of the direction ofdelivery and the encounter with the furnace interior, The taper wall isof advantage, afiording easy expan- I sion for the combustion productstoward the exit and ready clearance for the pigmentfumes from theassociated non-volatile constituents. Any suitable mechanism can beemployed for supplying the powdered charge as a burden to be floated inthe air-blast on its way to the furnace. Owing to the mode of deliveryand the copious volume of air and fuel supplies the combustion becomesin tense, the sulfur rapidly burns away, leaving the zinc free to reduceand convert into pigment-fumes, while the iron fuses in the flux andduring its swirling progress separates as a slag on contact with thefurnacewall.

Obviously the details of structure can be I furnace, setting the chargeafiaine, expand varied according to the mechanics skill withing theresultant pigment-fumes and comout departure from the invention. bustionproducts freely upward toward the Having thus described my invention,what exit and simultaneously separating and trap- 15' l 5 Iclaim as new,and desire to secure by Letters ping the associated non-volatileconstituents Patent, is or slags by arrest thereof during the centrifu-The method of making zinc-white which gal swirl, substantially asdescribed.

admixed charge of powdered ore, fuel and Witnesses: IO flux byprojecting it tangentially in divided GEO. P. FISHER, J r.,

consists in imparting a cyclonic swirl to the DAVID B. JONES; massesthrough aid of an air-blast into the I ALBERTA ADAMICK.

